Field
Aspects of the present invention generally relate to an image forming apparatus including a sensor and a method for controlling the image forming apparatus.
Description of the Related Art
Ecological awareness has been increasing in recent years. Under such circumstances, image forming apparatuses, such copying machines, are configured to reduce power consumption during standby by entering a power saving state where power supply to a printer unit and a scanner unit is stopped if the image forming apparatus is left unused for a predetermined time.
If a user uses an image forming apparatus currently in a power saving state, the user typically needs to press a button on the image forming apparatus for the image forming apparatus to recover from the power saving state. The user then usually needs to wait near the image forming apparatus until the image forming apparatus is ready to use. In view of this, image forming apparatuses have recently started to automatically recover from the power saving state if a nearby user is detected by a sensor for detecting user's (hereinafter, referred to as a human body detection sensor).
However, in many instances, image forming apparatuses are often installed in shared spaces. In addition to users of the image forming apparatus, there may also be passersby who simply pass by in the vicinity of the image forming apparatus. In this environment, the human detection sensor can sometimes detect a passerby and cause the image forming apparatus to erroneously recover from a power saving state. An image forming apparatus has therefore been desired that determines whether a person approaching the image forming apparatus is a user or a passerby.
Japanese Patent Application Laid-Open No. 2013-20048 discusses an image forming apparatus including an infrared array sensor including a plurality of elements for detecting heat around the image forming apparatus. According to Japanese Patent Application Laid-Open No. 2013-20048, the image forming apparatus recovers from the power saving state if a temperature distribution pattern obtained by the infrared array sensor is similar to a pre-stored pattern.
According to Japanese Patent Application Laid-Open No. 2013-20048, the recovery of the image forming apparatus from the power saving state is controlled, for example, by comparing a pattern representing a state where a user holds a document in the user's hand with the temperature distribution pattern obtained by the infrared array sensor. However, since the document held in the user's hand changes similarly to the surrounding environment in temperature, the presence or absence of the document is difficult to determine from the temperature distribution pattern obtained by the infrared array sensor. As a result, an erroneous detection can occur that results in recovery by the image forming apparatus from the power saving state even if the user is not holding a document.
The temperature of the surrounding environment does not just affect the document as described above. The surface temperature of a person is also affected by the temperature of the surrounding environment. For example, it is known that the surface temperature of a human hand is greatly affected by the temperature of the surrounding environment. It is therefore also difficult to identify a human hand from the temperature distribution pattern obtained by the infrared array sensor. It is known that the surface temperature of a human's abdominal region is less susceptible to the surrounding environment temperature, whereas the accurate surface temperature of the abdominal region is difficult to obtain by the infrared array sensor because of, for example, a person's clothing.
An image forming apparatus placed in various temperature environments needs to stably detect a person without being affected by the temperature of the surrounding environment.